Usually the cell suspensions received from doctors' clinics contain sample cells which have become aggregated or clumped together. To properly analyze this material, it is important to have a representative sample of single cells present on the microscope slide, with a minimum number of aggregated cell clumps. This is especially true for automated slide analysis.
A prerequisite for the screening of cytological material by an automated image analysis system is a reproducible and practical method for preparing smears of disaggregated cell suspensions. Many procedures have been described, for example, syringing, shaking, ultrasonic methods, and chemical methods, e.g., trypsinizing.
Of these, the most widely used is the syringing technique. This technique involves the use of a syringe typically having a 19-gauge needle. The cell suspension is drawn up into the syringe and then quickly expelled. The turbulent flow from the syringe shears and breaks up cell aggregates. This process is repeated many times, and can be done manually or automatically with a peristaltic pump. The difficulty with these techniques is that although effective, they are limited since they are labor-intensive and/or very time consuming.